In an earlier U.S. Pat. No. 4,821,462, issued Apr. 18, 1989 for Dental Instrument Sharpening Hone, by the same inventor, a hone for reconditioning dental instruments is disclosed that is characterized by a planar abrasive surface supported upon a base alongside of which a protractor element is mounted for rotation. The protractor element displays one or more straight lines whose angular relation to the abrasive surface can be changed by rotation of the element with respect to the abrasive surface so that the line or lines can be set to have the same angle with respect to the abrasive surface as the handle of the instrument has to the cutting surface of the tool which is carried by the handle.
In operation, the protractor element is adjusted to the desired rotation and fixed therein so as to position and maintain the indicia lines at a desired angle to the hone, depending on what instrument is being sharpened. The cutting edge of the dental instrument is then laid upon the hone with the angle of the instrument's handle positioned parallel to the indicia reference lines on the protractor element. As the cutting edge is manually drawn across the abrasive surface the handle is maintained at its initial angle to the hone, that is parallel with the line or lines on the protractor element.
The foregoing device is well suited to its intended purpose, however the infinite adjustability of the reference lines with the circular protractor element does not lend itself to compactness and simplicity.
Therefore, the primary purpose of the present invention is to provide a tool sharpening guide with non-movable parts and a more simplistic and economical construction, albeit with several fixed angles of reference lines rather than the infinitely variable selection of the former invention.
Another object of the present invention is to provide an instrument sharpening tool that can withstand being sterilized in a customary autoclave at soak temperatures in the vicinity of 275 degrees fahrenheit.
A further object of the invention is to provide a manual sharpening hone containing a reference angle guide which doubles as a hand steadying rest throughout the sharpening stroke.
Other and further objects, features and advantages of the invention will become apparent upon a reading of the following detailed description of a preferred form of the invention, taken in connection with the accompanying drawings: